In this project, amorphous calcium phosphate (ACP), an important intermediate in the formation of apatite, is being investigated for possible use as a dental material. When either used alone, or in combination with other dental materials, especially polymeric resins, ACP has a wide range of possible applications such as in restorative composites, cavity liners and bases, luting and pulp capping agents, prophylactic and endodontic sealants, and as a component in periodontic packs and impression pastes. It has a number of potential advantages over other calcium phosphates for these purposes. As a dental cement, its advantage over current biphasic systems (e.g., dicalcium/tetracalcium phosphate mixtures) is its simpler, single solid phase formulation. When included as a component in appropriate resin-based composites, sealants and adhesives, ACP may be useful as a remineralization agent as well as a vehicle for sustained, controlled release of inorganic anticaries ions such as fluoride. In this regard, chemical studies on various ACP-resin formulations indicate that ACP-embedded, methacrylate resins release calcium and phosphate ions at levels that exceed the thermodynamic minimum necessary for remineralizing damaged tooth surfaces. Currently, in vitro studies on bovine teeth are being carried out to evaluate the suitability of ACP-resin composites as remineralizing dental sealants. Results to date indicate that in artificial saliva-like test solutions, significantly higher levels of remineralization occur in tooth lesions coated with ACP- containing resins compared to uncoated lesions or those coated with silica- or apatite-containing resins.